ruggables.com area rug and Behr Oslo Blue paint for accent wall. keep the furniture, lamp and bedding.

I agree a rich paint color like that Oslo Blue would make the items in here really pop. A larger rug. A Jade green bolster pillow for the bed.

I would get right size rug, curtains and wall art above the headboard.

You could always paint the headboard a fun color. Look through photos on Houzz to come up with an inspiration photo.

I would have a really hard time using bedding left by the previous owners ... specially if it had been used as a rental.

It looks like a large rectangular piece of artwork would work well over the bed, a large rug seems to be needed and some accent colors. Maybe a shade of blue? You could get some blue lamps, a rug with some blue in it, and some pillows and a blanket that are blue to add to the bed.

Cheerful Family Home · More Info

I would paint headboard with black.